Answer
Foci: $(0, \pm \sqrt 2)$
Vertices : $(0, \pm 2)$
Work Step by Step
$\frac{x^2}{2}+\frac{y^2}{4}=1$
Rewrite as $\frac{x^2}{(\sqrt 2)^2}+\frac{y^2}{(2)^2}=1$
$c^2=a^2-b^2=(2)^2-(\sqrt 2)^2=2$
$c=\sqrt 2$
Foci: $(0, \pm \sqrt 2)$
Vertices : $(0, \pm 2)$